U.S. patent number 4,027,889 [Application Number 05/630,093] was granted by the patent office on 1977-06-07 for stair-climbing carrier.
This patent grant is currently assigned to Kando Incorporated. Invention is credited to Andrew D. Dodds, Gary F. Krofchalk.
United States Patent |
4,027,889 |
Krofchalk , et al. |
June 7, 1977 |
Stair-climbing carrier
Abstract
A tracked, stair-climbing carrier for carrying loads up and down
stairs and across floors. The carrier includes a frame mounting a
pair of parallel endless tracks at its sides for moving the frame
forwardly and rearwardly along a floor and up and down stairs. An
upper, load-receiving deck is slideably carried by the frame and is
movable forwardly and rearwardly to adjust the center of gravity of
the carrier and load and permits the rearward end of the deck to
rest upon the floor when the frame has been tilted to an acute
angle with the floor. A load-bearing lifting arm, receivable in the
frame between the tracks, may be swung downwardly to cause the
forward end of the frame to tilt upwardly at an acute,
stair-engaging angle to the floor, the tilted frame with the deck
and load being supported rearwardly by the tracks or supplemental
wheels and forwardly by casters at the forward, downwardly swung
end of the lifting arm, whereupon the tilted, fully supported and
balanced load may be moved along the floor with the tracks in
position to engage stairs, ramps, curbs, etc.
Inventors: |
Krofchalk; Gary F. (Rochester,
MN), Dodds; Andrew D. (Claremount, MN) |
Assignee: |
Kando Incorporated (Claremont,
MN)
|
Family
ID: |
24525722 |
Appl.
No.: |
05/630,093 |
Filed: |
November 10, 1975 |
Current U.S.
Class: |
280/5.22;
180/9.22 |
Current CPC
Class: |
B62B
5/02 (20130101); B62B 2301/256 (20130101) |
Current International
Class: |
B62B
5/02 (20060101); B60P 009/00 () |
Field of
Search: |
;280/5.22,5.24,5.3,5.28,5.32,28.5 ;305/1,2 ;180/9.22 ;187/11
;214/1,2 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
Other References
SI.M. Equipment Limited "Alouette" Mar. 30, 1964..
|
Primary Examiner: Goodman; Philip
Attorney, Agent or Firm: Palmatier; H. Dale
Claims
What is claimed is:
1. A tracked carrier for carrying loads in a tilted position across
floors and up and down stairs, and comprising
an elongate load-carrying frame with means to which a load may be
attached along the elongate frame, the frame having upper and lower
ends,
a spaced pair of elongate, parallel, endless tracks extending along
opposite sides of the frame and being movable in elongated paths to
drive the frame along a supporting surface and up and down stairs,
the tracks extending beyond the lower end of the frame to support
the frame upon such a supporting surface when the frame is tipped
to upright and inclined positions;
a lifting arm pivotally mounted at one end to the frame adjacent
the lower end thereof, and having a floor-engaging caster at its
other end, the lifting arm being configured for reception within
the frame between the tracks when swung upwardly into a retracted
position with the caster nearer the upper than the lower end of the
tracks, and the arm being swingable to near horizontal position
when the elongate frame is supported in upright position on the
lower ends of the elongate endless tracks and against a load to be
tipped into inclined transport position; and
means for controllably swinging the lifting arm outwardly from its
retracted position to support the frame in an inclined angle with
the floor for travel therealong on the caster wheel and the lower
ends of the elongate endless tracks.
2. The carrier of claim 1 wherein said means for swinging the
lifting arm comprises an axially extensible thruster extending
between the lifting arm and the frame of the carrier.
3. A tracked carrier for carrying loads in a tilted position across
floors and up and down stairs, and comprising
a frame carrying at its sides a spaced pair of parallel, endless
tracks movable in elongated paths to drive the frame along a
surface and up and down stairs;
a lifting arm pivotally mounted at one end to the frame adjacent
the rear of the frame and having a floor-engaging caster at its
other end, the lifting arm being configured for reception within
the frame between the tracks when swung upwardly into a retracted
position with the caster nearer the forward than the rearward end
of the tracks; and
means for controllably swinging the lifting arm outwardly from its
retracted position to tilt the frame into an acute, stair-engaging
angle with the floor with the center of gravity of the carrier
spaced rearwardly of the caster, whereby the tilted carrier and any
load carried thereby are balanced and supported rearwardly by the
rearward ends of the tracks and forwardly by the caster for
movement along a floor, said means for swinging the lifting arm
comprises a pair of thrusters lying in a common plane and a bracket
pivotally connected to the forward ends of the thrusters and
pivotally connected to the forward end of the frame to permit
pivoting of the bracket about an axis normal to the plane of the
thrusters for accommodation of unequal rates of extension or
retraction of the thrusters, and a thruster-actuated cam pivotally
mounted to the lifting arm for rotation in response to extension or
retraction of the thrusters, and a cam follower mounted to the
frame, the cam being configured to force the cam follower upwardly
in response to extension of the thrusters to swing the lifting arm
outwardly from the frame.
4. A tracked carrier for carrying loads in a tilted position across
floors and up and down stairs, and comprising
a frame carrying at its sides a spaced pair of parallel, endless
tracks movable in parallel, elongated paths to drive the frame
along a surface or up and down stairs;
a lifting arm swingably mounted at one end to the frame and having
a floor-engaging caster at its other end, the lifting arm being
configured for reception within the frame between the tracks when
swung upwardly into a retracted position; and
means for controllably swinging the lifting arm outwardly from its
retracted position to tilt the frame into an acute, stair-engaging
angle with the floor and comprising a cam with an arcuate camming
surface pivotally mounted to the lifting arm along its length, a
cam follower mounted to the frame in cam-engaging position, and at
least one axially extensible thruster mounted at one end to the
frame and at its other end to the cam to rotate the latter, the
camming surface being configured to force the cam follower upwardly
in response to rotation of the cam by extension of the thruster,
thereby initiating outward movement of the lifting arm from the
frame.
5. The carrier of claim 4 including a spaced pair of axially
extensible thrusters lying in a common plane, and including a
bracket pivotally and individually mounting the thrusters at their
forward ends to the forward end of the frame and pivotal about an
axis normal to the plane of the thrusters to accommodate unequal
rates of thruster extension.
6. The carrier of claim 5 including a separate power source for
each thruster to extend and retract the same, each source of power
being mounted to the respective thruster and movable with the
thruster as the latter is extended and retracted.
7. The carrier of claim 6 including a bracket holder pivotally
mounting the thruster bracket to the forward end of the frame for
pivotal movement about a transverse axis and permitting the
thrusters to change angles with respect to the floor as they are
extended and retracted.
8. An easily loaded and unloaded tracked carrier for carrying loads
in a tilted position across floors and up and down stairs and
comprising
a frame carrying at its sides a spaced pair of parallel, endless
tracks movable in elongated paths to drive the frame along a floor
and up and down stairs;
a lifting arm having a caster at one end and mounted at its other
end to the frame, the lifting arm being movable outwardly from the
frame to tilt the frame forwardly and upwardly into an acute angle
with the floor with the center of gravity of the frame falling
rearwardly of the caster;
an upper deck for bearing a load and slideably carried by the frame
for movement rearwardly thereof to permit the rearward end of the
deck to project rearwardly of the rearward end of the tracks;
and
load-adjustment means for moving the deck forwardly or rearwardly
of the frame to adjust the center of gravity of the carrier and its
load over the tracks and permitting the rearward end of the deck to
rest on the floor to the rear of the tracks when the frame has been
lifted to form said acute angle with respect to the floor, to
thereby facilitate loading and unloading the carrier.
9. The carrier of claim 8 wherein the deck, at its rearward end,
includes an outwardly projecting toeplate for engaging loads and
preventing movement of the loads rearwardly of the deck.
10. The carrier of claim 8 wherein the load adjustment means
includes a frame-mounted winch and a winch cable extending from the
winch and attached to the deck, and wherein the frame and deck have
coacting guides and guide followers for guiding the deck forwardly
and rearwardly of the frame in response to operation of the
winch.
11. An easily loaded and unloaded, tracked, stair-climbing,
adjustable-balance carrier for carrying loads up and down stairs
and across floors, and comprising
a generally flat, elongated frame having sprockets at its front and
rear, and a pair of spaced, endless, parallel lugged tracks trained
over the sprockets for movement of the frame forwardly or
rearwardly;
a lifting arm comprising a pair of spaced, generally parallel and
coextensive lever arms each mounted at one end to the frame
adjacent the rear of the frame and having a floor-engaging caster
at its other end, the lever arms being configured for reception
within the frame between the tracks when swung upwardly into a
retracted position with the casters nearer the forward than the
rearward end of the tracks;
means for swinging the lifting arm outwardly from its retracted
position to tilt the frame into an acute, stair-engaging angle of
about 30.degree. - 40.degree. with the floor with the center of
gravity of the carrier spaced rearwardly of the casters, and
including an elongated, extensible and retractable thruster
pivotally mounted at opposite ends to the frame and arm to rotate
the latter, and a bracket pivotally mounted to the forward end of
the frame and having a pivot separately mounting the forward end of
the thruster thereto;
an upper deck slidably mounted on the frame for carrying a load and
slidable along the frame forwardly thereof and also rearwardly
thereof to the extent that the rearward end of the deck projects
beyond the rearward end of the tracks to the floor when the frame
is in its tilted position; and
a drive mechanism connecting the deck and frame to move the deck
and any load borne by the deck forwardly and rearwardly of the
frame;
whereby the carrier in a tilted position, and any load carried
thereby, may be balanced and supported rearwardly by the rearward
ends of the tracks and forwardly by the casters for movement along
a floor and whereby the load may be adjusted so that the center of
gravity of the load and carrier falls safely over the tracks for
climbing of stairs.
12. The carrier of claim 8 including a platform releasably mounted
to the rearward ends of the deck and extending outwardly from the
deck, the platform having at least one rearwardly extending caster
at its outer end in position to engage the floor when the deck is
in a raised, upright position, whereby the carrier and any load
thereon is supported forwardly by the rearward end of the tracks
and rearwardly by at least one platform caster.
13. The carrier of claim 8 including bogie wheels releasably
mounted to the frame adjacent the rearward ends of the tracks and
oriented to engage and disengage the floor as the carrier is tilted
to varying predetermined angles with the floor.
14. A tracked carrier for carrying loads in a tilted position
across floors and up and down stairs, and comprising:
an elongate load-carrying frame with means to which a load may be
attached along the elongate frame, the frame having upper and lower
ends,
a pair of elongate, parallel and endless tracks extending along
opposite sides of the frame and being movable in elongated paths to
drive the frame along a supporting surface and up and down stairs,
the tracks extending beyond the lower end of the frame to support
the frame upon such a supporting surface when the frame is tipped
to upright and inclined positions;
a lifting arm having an inner end pivotally mounted on the frame
adjacent the lower end thereof and having an outer end with a
floor-engaging caster thereon, the lifting arm being configured for
reception within the frame between the tracks when swung into
retracted position;
a source of rotary power on the frame and including drive mechanism
connected to said endless tracks and applying driving impetus to
both of the tracks, said drive machanism including differential
gearing through which such power is applied to the separate tracks,
and
means for controllably swinging the lifting arm outwardly from its
retracted position to support the frame in an inclined angle with
the floor for travel therealong on the caster wheel and the lower
ends of the elongate endless tracks, the differential gearing and
caster wheel facilitating steering during travel along the floor,
and the differential gearing permitting steering during travel on a
stairway with the caster wheel retracted.
15. The tracked carrier according to claim 14 and including a
load-carrying platform having a lower end adjacent the lower end of
the frame, the platform being slidably mounted on the frame and
movable to extend the lower end of the platform downwardly beyond
the lower end of the frame and beyond the adjacent end of the
endless track, and the platform also being slidable upwardly along
the frame to a position wherein the lower end of the platform is
disposed between the ends of the frame and between the ends of the
endless tracks thereon.
Description
BACKGROUND OF THE INVENTION
Large, heavy objects such as file cabinets and refrigerators must
often be moved from one floor to another within a warehouse of
office building or the like. Although such objects can easily be
moved along a level floor by use of a "dolly" or handtruck,
difficulty is experienced in moving objects of this type from one
floor to another in the absence of elevators. Such bulky and
weighty objects are ordinarily "manhandled" up and down stairs;
that is, the objects are physically lifted by a team of workmen and
carried up and down stairs. Labor costs are thus high, and the
chances of injury are large.
Efforts have been made in the past to provide mechanical carriers
for carrying large objects up and down stairs; representative of
these carriers are those of U.S. Pat. Nos. 2,928,501 and 3,512,658.
These devices are not easily loaded and unloaded, however, and
either require the use of a separate "dolly" in conjunction with
stair climbing or require a human operator to bear a portion of the
weight of the load as the load is moved.
BRIEF DESCRIPTION OF THE INVENTION
The present invention provides a tracked carrier which moves along
a floor in a tilted position supported rerwardly by the tracks or
supplemental wheels and forwardly by a lifting arm. It its tilted
position, the carrier of the invention is adapted to encounter and
ascend stairs. No weight-bearing human effort is required to load
and unload the carrier, nor does the carrier normally require the
use of an additional dolly or handtruck for operation.
The tracked carrier of the invention includes a frame carrying a
spaced pair of parallel endless tracks at its sides movable in an
elongated path to drive the frame forwardly and rearwardly along a
surface. A lifting arm is pivotally mounted at one of its ends to
the frame between the tracks and adjacent the rearward end of the
frame, and is movable between a retracted position and a
load-bearing position. At its other end, the lifting arm has one or
more floor-engageably casters which are nearer the forward than the
rearward ends of the tracks when the arm is in its retracted
position. Means are provided for controllably pivoting the lifting
arm outwardly and downwardly from the frame about its pivot point
into a load-bearing position to raise the forward end of the frame
and to thus tilt the frame to form an acute, stair-engaging angle
with respect to the floor with the center of gravity of the carrier
spaced rearwardly of the casters. In its load-bearing position, the
lifting arm coacts with the tracks to carry the load at the acute
angle with respect to the floor, in which position the load may be
moved along the floor. Slideably mounted to the frame for forward
and rearward movement is a load-receiving deck, and the carrier
includes load adjustment means for moving the deck forwardly or
rearwardly of the frame to adjust the center of gravity of the
carrier and its load over the tracks. The load adjustment means
permits the rearmost end of the deck to extend rearwardly of the
rearward end of the tracks to rest on the floor when the frame is
tilted to form said acute angle with the floor to facilitate
loading and unloading.
The means for pivoting the lifting arm includes at least one and
desirably a pair of powered, axially extensible thrusters lying in
a common plane and each joined at one end to the frame. At their
other ends, the thrusters are mounted to a cam carried by the
lifting arm and engageable with a frame-mounted cam follower to
initiate outward swinging of the lifting arm. A T-shaped bracket
mounts the thrusters pivotally to the frame and pivots about an
axis normal to the plane of the thrusters to allow for non-uniform
extension of the thrusters as the lifting arm swings downwardly and
outwardly.
The load, such as a filing cabinet, may be attached to the deck
when the latter is in an upright position. The carrier is then
tipped into its tilted position, the deck sliding rearwardly to
maintain contact between its lower, rearward end and the floor. The
deck is then slid forwardly and upwardly on the frame to position
the center of gravity of the load between the rearward end of the
tracks and the lifting arm casters. The well balanced and supported
tilted load may be moved along a floor with the carrier in position
at an angle to the floor to engage the treads of a stairway.
BRIEF DESCRIPTION OF THE DRAWING
FIGS. 1-5 are elevational views of the carrier of the invention
with load attached, showing the carrier and load in different
positions as the load is loaded and transported across a floor and
up a flight of stairs;
FIG. 6 is an oblique view taken along line 6--6 of FIG. 3;
FIG. 7 is a side view of the carrier in cross section with the
frame tilted;
FIG. 8 is a cross-sectional view taken along line 8--8 of FIG.
6;
FIG. 9 is a top view taken along 9--9 of FIG. 8, and showing a
modification in the winch and cable;
FIG. 10 is a partial, broken away, cross-sectional view taken along
line 10--10 of FIG. 9;
FIG. 11 is a side view of a modified form of the invention;
FIG. 12 is a perspective, broken away view of a portion of the
device shown in FIG. 11; and
FIG. 13 is a side view of the carrier of the invention of FIG. 9 as
the carrier is loaded.
DESCRIPTION OF THE PREFERRED EMBODIMENT
Referring first to FIGS. 6-10, the carrier 10 of the invention
includes a generally flat, elongated frame designated generally as
12, and endless tracks 14 carried on either side of the frame and
movable in an elongated path to drive the frame forwardly and
rearwardly along a surface. At its top, the frame carries a
forwardly and rearwardly slideable deck 16 for carrying loads. A
lifting arm 18 is pivotally mounted at its rearward end to the
rearward end of the frame and is received within the frame between
the tracks in its retracted position, as shown in FIG. 8. Means
(designated generally 20) are provided for controllably pivoting
the lifting arm 18 downwardly and outwardly from the frame as shown
in FIG. 7 to tilt the front of the frame upwardly into a
stairway-engaging position. Balance adjustment means, designated
generally as 22, is provided to move the deck 16 forwardly and
rearwardly along the track as desired, and permits the deck to
engage the floor even when the frame is in its tilted position, as
shown in FIG. 2. The forward end of the lifting arm 18 is provided
with casters 24 which extend forwardly of the center of gravity of
the carrier when the lifting arm is retracted as shown in FIG. 8
and also when the lifting arm is in its extended position as shown,
for example, in FIG. 2.
The Frame 12 is of generally parallelepiped shaped and includes
forwardly and rearwardly extending deck support bars or guides 12.1
which are rigidly connected by transverse support bars 12.2, 12.3,
shown best in FIG. 6. A mounting platform 12.4 for mounting a gear
reduction unit 12.5 and motor 12.6 extends between the rail 12.1
adjacent the rear of the frame, as shown best in FIG. 6. The motor
and gear reduction units have been omitted in FIGS. 7 and 8 for
purposes of clarity.
Forwardly and rearwardly extending braces 12.7 are carried beneath
the respective deck guides 12.1 by forward and rearward brackets
12.8, 12.9 at the sides of the frame. Affixed to the bottom of the
braces 12.7 are track guide bars 13 having nylon wear strips 13.1
affixed to their bottom surfaces. A tie rod 13.2 is connected
between the bottom ends of the front brackets 12.8, 12.9 as shown
in FIGS. 7 and 8.
A rear axle 14.1 is provided with differential gearing 14.2 and is
carried by bearing blocks 14.3 mounted to the frame at the rear of
the braces 12.7. Carried by the axle 14.1 at either end are toothed
sprockets 14.4. Another pair of toothed sprockets 14.5,
freewheeling, are mounted on axles 14.6 which in turn are carried
on bearing blocks 14.7 mounted to the forward ends of the braces
12.7
Extending about the toothed sprockets 14.4, 14.5 at either side of
the frame are endless tracks 14. As shown in FIG. 6, each track may
be provided with spaced holes 14.8 centrally along its length to
receive the teeth of the toothed sprockets 14.4, 14.5, and may be
reinforced by including therewithin a drive chain to receive the
sprocket teeth between the rollers thereof. Desirably, the outer
surfaces of the tracks are unbroken, and the inner surfaces of the
tracks may be provided with suitable depressions between the chain
rollers to engage the teeth of the toothed sprockets. The outer
surfaces of the tracks are provided with outwardly extending lugs
14.9 to enable the tracks to engage stair steps without slipping.
The tracks, as thus described, are driven through elongated paths
by rear sprockets 14.4 driven through the axle 14.1 through
differential 14.2, gear reduction unit 12.5 and motor 12.6. In its
rearward run from the forward sprockets 14.5 to the rear sprockets
14.4, the tracks are slideably supported against the nylon strips
13.1.
The deck 16 is formed of a rectangular metal plate 16.1 of
sufficient dimensions to substantially cover the entire top of the
frame 12. The plate is supported from beneath by a framework
including a pair of longitudinally extending inner and outer deck
braces 16.2, 16.3 on either side of the metal plate, a transverse
brace 16.4 at the front edge of the deck, and a transverse rear
brace 16.5 at the rear edge of the deck, as well as other
transverse braces. Longitudinal braces 16.3 extend rearwardly for a
short distance beyond the deck plate 16.1, and are joined
transversely at their rearward ends by a pair of parallel, spaced
bars 16.6, 16.7, as shown best in FIGS. 7-9. The upper surface of
the bar 16.6 is spaced below the upper surface of the deck plate
16.1 so as to accommodate the thickness of a toeplate 17. As shown
best in FIGS. 7 and 9, the toeplate includes a flat, central
portion 17.1 which rests upon the upper surface of the bar 16.6 and
which has an upwardly turned lip 17.2 at its rearward end. At its
forward end, the toeplate has a downwardly and rearwardly turned
hook 17.3 which hooks downwardly over the leading edge of the bar
16.7 into the space between bars 16.7 and 16.6. The upper surface
of the bar 16.7 is depressed slightly to allow some play between it
and the toeplate 17, as shown in FIG. 7, so that the toeplate can
be removed easily from the deck.
To the upper surface of the deck 16 are affixed one or more wear
strips 17.4 of rubber of the like to engage the load to be placed
on the deck. Downwardly and inwardly protruding guide followers,
shown as right angled strips 16.8 in FIG. 10, are mounted to the
deck framework and coact with similar, inverted angled strips 16.9
on the longitudinal frame bars 12.1 to guide the deck forwardly and
rearwardly with the deck brace 16.2 riding upon a slip plate 12.11
of nylon or the like attached to the frame bar 12.1 (FIG. 10). If
desired, the deck plate itself may be omitted, and loads may be
carried on the deck frame.
A winch is mounted to the forward end of the carrier frame 12 and
includes a winch drum 22.1, a generally forwardly extending crank
handle 22.2, and a common, releasable ratchet and pawl mechanism
22.21 for rotating the drum by cranking the handle 22.2. As shown
in FIGS. 7 and 8, a cable 22.3 is wound at one end around the drum
and extends rearwardly along the bottom surface of the deck
approximately midway between the deck sides. The cable terminates
rearwardly in a hook 22.4 which engages, in turn, an eyebolt 22.5
which is attached to the leading surface of the deck brace 16.5.
Operation of the winch hence causes the deck 16 to move forwardly
or rearwardly along the frame 12 of the carrier and permits the
rearward end of the deck to extend rearwardly of the rearward end
of the tracks, the significance of which will be subsequently
explained.
In the cable modification shown in FIG. 9, the cable 22.3 leads
from the winch drum about a central, frame-mounted pulley 22.3a and
extends rearwardly beneath the deck to pass about a deck-mounted
pulley 22.3b. The cable then returns forwardly beneath the deck, is
trained about pulley 22.3c mounted at the leading edge of the deck
frame, and then extends rearwardly above the deck and terminates in
hook 22.4 which may be attached to the deck or to a load to be
pulled onto the deck, as shown in FIG. 13. A manually operated deck
latch 22.4a serves to lock the deck to the carrier frame when a
load is to be pulled onto the deck.
A lifting arm 18, shown best in FIGS. 6-8, includes a pair of lever
arms 18.1, 18.2 spaced apart and joined pivotally at their rearward
ends, at pivots 18.3, to the respective rearward ends of the frame
braces 12.7. The lever arms extend forwardly and are fully
receivable within the frame between the tracks of the carrier.
Intermediate their length, the lever arms have convergent sections
18.4, 18.5, which lead into parallel, spaced, forwardly extending
sections 18.6, 18.7, respectively. Horizontal battery mounting
plates 18.8, 18.9 are attached in outrigger-fashion to the sides
from the last-identified lever arm sections. The sections 18.6,
18.7 terminate forwardly in caster mounting plates 19, 19.1,
respectively, and caster (full circle swivel wheels) 24 are mounted
to the bottom of the plates 19, 19.1. The lever arms are connected
to one another by forward transverse strut 19.2 at their forward
ends and a rearward transverse strut 19.3 at the rearward ends of
the convergent portions 18.4, 18.5. The dimensions of the lifting
arm are so chosen that when the lifting arm is fully received
within the frame (as in FIG. 8), the casters 24 are lifted
completely above the level of the tracks 14 so as not to interfere
with the tracks.
As shown best in FIGS. 6-8, a cam 26 is pivotally mounted to the
lever arms 18.1, 18.2 for swinging movement between the arms. The
cam includes a baseplate 26.1 having outwardly turned, curved cam
edges 26.2 at its sides. The cam edges 26.2 are pivotally mounted,
as with bolts, to ears 26.3 mounted to the upper surface of the
lever arms at points intermediate their length so that as the cam
is pivoted, the cam edge moves through the positions shown in FIGS.
7 and 8. To the transverse bar 12.2 of the frame 12 are affixed
downwardly projecting rollers 26.4 which serve as cam followers,
and which are positioned to contact and roll against the curved cam
edges 26.2 as the cam is pivoted, as shown in FIGS. 7 and 8.
Movement of the cam 26 (FIG. 8) is a clockwise direction hence
forces the rollers 26.4 upwardly and raises the frame with respect
to the lifting arm 18 (FIG. 7).
Means 20 for forcefully pivoting the cam 26 about its pivotal
connections to the lifting arm includes a pair of thrusters shown
generally as 20.1 which extend between the frame and the cam. The
thrusters 20.1 are generally parallel or very slightly divergent
forwardly, as shown in FIG. 6, and each of the thrusters is
pivotally joined at its rearward end 20.2 to a transverse pivot bar
20.3 carried between the cam edges 26.2 at the forward and downward
end of the cam and further supported by ears 26.5 mounted to the
cam baseplate 26.1. From the thus-described pivotal attachment, the
thrusters 20.1 extend forwardly and upwardly for mutual pivotal
connection between the upper and lower plates 20.4, 20.5 of a
bracket 20.6. Pivot pins 20.7 passing through the plates and the
thrusters. As shown in FIG. 6, the thrusters are spaced from one
another at their points of attachment to the cam 26 and to the
bracket 20.6.
The bracket 20.6, in turn, is pivotally connected to a generally
U-shaped bracket holder 20.8. The arms of the bracket holder extend
rearwardly and downwardly above and below the respective plates of
the bracket 20.6 and are pivotally connected to the plates by means
of a bolt 20.9. The forward crossbar of the U-shaped bracket holder
20.8 is pivotally connected to the frame 12 of the carrier through
a transverse pivot pin 21 which passes through ears 21.1 extending
rearwardly of the frame support bar 12.3. The pivot pin 21 thus
permits the bracket holder 20.8, and the bracket 20.6, to move
upwardly and downwardly between the position shown, for example, in
FIGS. 7 and 8. The pivot pins 20.7 and 20.9, moreover, permit the
bracket 20.6 to pivot to the right or left with respect to the
bracket holder 20.8, and in this manner some unevenness in the rate
of extension or retraction of the thrusters 20.1 is permitted.
Each of the thrusters or actuators, 20.1, are provided internally
with mating, male and female threaded tubes whereby rotation of one
of the tubes causes the other tube to move along the axis of the
thruster and to pivot the cam 26 about its pivotal connection to
the lifting arm 18. Each thruster is provided with its separate
power supply 30 including an electric motor 30.2 and drive belt
30.3, these power units being mounted to, and carried by, the
forward ends of the thrusters which extend forwardly through the
bracket 20.6. The motors 30.2 and 12.6 (the latter driving the
track 14) may be reversible, direct current motors which draw power
from batteries (not shown) supported on battery mounting plates
18.8, 18.9. The motors 30.2 are operated in unison to cause
simultaneous extension or retraction of the thrusters 20.1. The
pivotally mounted bracket 20.6, which allows for differences in the
extension or retraction rates of the thrusters, lends flexibility
to the system and effectively prevents any binding of the
thrusters, cam and cam follower rollers.
The electrical system for the carrier of the invention, which for
reasons of clarity is not shown in the drawing, includes electric
leads running to each of the electric motors 30.2, 12.6 and to the
batteries, and leading to connector box 32 which is mounted to a
forward portion of the frame. A multi-wire lead 32.1 extends
forwardly from the box 32 and terminates in switch box 32.2 (see,
e.g., FIG. 4) which has switches for energizing the motors 30.2,
12.6 and for reversing the rotation of the motors. A generally
cylindrical electric plug 32.2 is pluggable rearwardly into the
connector box, and from the plug extends a multi-wire lead 32.1
terminating forwardly in a switch box 32.2 (see e.g., FIG. 4) which
has switches for energizing, and reversing the rotation of, the
motors 30.2, 12.6. Transverse locking pins 32.4, 32.5 are slidably
mounted to the carrier frame by spring-loaded brackets 32.6 which
spring-urge the locking pins respectively outwardly into contact
with the sprockets 14.5 to prevent the latter from turning. The
locking pins each extend inwardly beneath the plug 32.3 and have
upwardly turned ends 32.7, 32.8 which bear against the plug, as
shown best in FIG. 6, the plug hence preventing the pins from
sliding outwardly to contact the sprockets 14.5. Should the plug be
pulled from the connector box (as, for example, when the carrier
tips rearwardly), the locking pins are freed to snap outwardly and
lock the track against further movement. Downward force applied to
the arm 18, of course, will permit the carrier and load to assume
the position shown in FIG. 2.
A T-shaped handle 34 protrudes forwardly of the frame and is
rigidly attached to the frame support bar 12.3, the handle being
utilized for pulling the load in the position shown in FIG. 3
across the floor and for otherwise manipulating the carrier.
The frame of the carrier, and the deck framing, is preferably made
of lengths of metal tubing having a generally rectangular cross
section, the sections of tubing being desirably welded together for
strength. This type of construction permits ready assembly of the
carrier. For example, the bearing blocks 14.7 which bear the front
sprockets 14.5 may have rearwardly extending tubular members which
are received within, and then bolted to, the tubular longitudinal
frames 12.7. An extra pair of wheels, shown as 36 in phantom lines
in FIG. 7 and termed "bogie" wheels, may be mounted on bearing
blocks similar to the bearing blocks 14.7 and having short,
forwardly protruding tubular mounting rods which are receivable
within the short tubing sections 13.4 mounted to the rear of the
frame. Generally forwardly and downwardly protruding tubing
sections 13.4a are provided to permit the bogie wheels 36 to be
mounted slightly forwardly of the rear end of the track. The bogie
wheels may be employed when loads are to be moved over a
substantial horizontal distance, and operate to lift the rearward
end of the track from the surface so that the load is supported
entirely by the bogie wheels and the casters 24. Power from the
track motor 12.6 may be conveyed to the gear box 12.5 by means of a
drive belt 12.51, and from the gear box to the differential gear
14.2 by means of a drive chain 12.52, as shown in FIG. 6.
FIGS. 11 and 12 show a rear, wheeled platform 40 removably attached
to the carrier deck frame for transporting large objects such as
file cabinets in an upright position along a generally level
surface. The platform includes a generally U-shaped frame having
legs 40.1 and cross bar 40.2. The free ends 40.3 of the legs are
bent so as to make angles with the legs of slightly greater than
90.degree.. As shown in FIG. 12, the angle A may be, for example,
about 95.degree.. The ends 40.3 of the legs, which may be
rectangular in cross section, are received in tubular receptacles
40.4 parallel to and rigidly fastened as by welding to the
respective outer longitudinal deck braces 16.3 near the rearward
ends of the braces. The ends 40.3 of the platform legs fit loosely
in the receptacles 40.4 so that when rearward pressure is exerted
on the platform (as in FIG. 11), the legs ends bend in the
receptacles with the legs making approximately a right angle with
the deck. Additional braces (not shown) may extend between the legs
and the cross bar 40.2 to rigidify the platform as shown in FIG. 11
so that the load L is supported on the platform forwardly by the
carrier tracks and rearwardly by the casters, in which position the
load may be transported up or down gradual inclines or across a
level surface by the tracks. Because of the forward and rearward
movement afforded the deck, the deck and platform 40 coact to
provide a lift or elevator for raising and lowering the load, as
indicated by the solid line and phantom line positions in FIG.
11.
As described elsewhere, the toeplates 17 may be easily removed so
that a load L may be winched onto the deck, as shown in FIG. 13. To
load the carrier in this manner, the carrier is first positioned at
a small angle to the horizontal, as shown in FIG. 13, and deck
latch 22.4a (FIG. 6) is thrown to lock the deck to the carrier
frame, Auxiliary ramps 42 are placed in position between the floor
and the rear of the deck, the cable hook 22.4 is attached to the
load L, and the load is winched up the ramps and onto the deck. The
toeplate 17, or platform 40, is then mounted to the deck to prevent
the load from sliding rearwardly. The deck latch is then opened,
and further winching causes the deck and load to slide forward to
the desired balanced position.
Operation of the carrier of the invention may be readily understood
by reference to FIGS. 1-5 wherein L denotes a load to be carried by
the carrier across a level floor F and up a flight of stairs S.
With reference to FIG. 1, the carrier 10 of the invention is moved
into an upright position with the toeplate 17 resting substantially
on the ground, and the carrier is pushed up against the sides of a
load (such as a filing cabinet) with the toeplate 17 slipping under
the near edge of the load. A belt B may be wrapped about the filing
cabinet as depicted, with the ends of the belt attached to the deck
of the carrier by means of small, downwardly and inwardly
protruding fingers 17.5 (FIGS. 9 and 10) which are attached to the
deck framework. The carrier is then tilted forwardly into the
position shown in FIG. 2, the deck being permitted to slide
rearwardly upon the frame so that the toeplate 17 of the deck
remains in contact with the floor. At this point, the weight of the
load is supported primarily by the toeplate 17 and the rearward
portion of the track 14, with some of the weight of the load and
carrier being born by the casters 24 at the front of the lifting
arm 18. The center of gravity of the load and carrier, however, is
to the rear of the midline of the frame of the carrier.
The deck is then advanced forwardly and upwardly on the carrier
frame by cranking of the handle 22.2 (FIG. 9) until the load
assumes the position shown in FIG. 3 in which the center of gravity
of the load and carrier falls well between the rear of the track 14
and the casters 24. In this balanced condition, the load may be
readily transported across the floor F by movement of the tracks.
The bogie wheels referred to above may be employed to render the
carrier freewheeling, and the carrier may be readily moved along
the floor with minimum manual force.
When an upwardly sloping flight of stairs is encountered, the
carrier is advanced to the foot of the stairs with the casters 24
approaching the bottom step. The lifting arm 18 is then
controllably retracted into the frame of the carrier, which results
in the leading end of the track being brought downward into contact
with the treads of the stairs above the first step or two. The
lifting arm is then further retracted completely within the frame,
as shown in FIG. 4, and the carrier and load are advanced up the
stairs by operation of the tracks. In this position, the center of
gravity of the load and carrier are maintained between the ends of
the track so that there is no tendancy of the load to tip forwardly
or rearwardly. Movement of the deck forwardly or rearwardly of the
carrier frame to maintain this balance may be easily accomplished
by cranking the crank handle 22.2, as discussed above.
When the carrier has reached the top of the stairs, as shown in
FIG. 5, the carrier is permitted to tip gently down into contact
with the top floor FF, the center of gravity of the load and
carrier being maintained between the forward and rearward ends of
the track. The carrier and load may then traverse the floor FF with
the carrier track resting fully on the floor, or the lifting arm
may be energized by operation of the switch box 32.2 so as to cause
the lifting arm to extend downwardly from the carrier frame, as
shown in FIG. 6, so that the load is again supported at an angle to
the floor. The load may be moved down stairways by simply reversing
the above procedure, the toeplate 17 in each instance remaining at
the lower end of the load.
When the load is supported in the position shown in FIG. 3, it will
be understood that the load and carrier may be pivoted about the
rear of the track with ease, and separate handtrucks or other
equipment ordinarily are not required. The length of the lifting
arm 18 is such that when the load is in the tilted position shown
in FIG. 3 (the frame making an angle with the floor of about
30.degree.-40.degree.), the caster 24 is approximately beneath the
leading end of the track so as to offer well-balanced support to
the load L. In other words, provided the center of gravity of the
load L and carrier is maintained between the lower end of the track
and the casters 24, no forward or rearward tipping of the load can
occur, and the load may be lowered to a substantially horizontal
position or raised to the tilted position of FIG. 3 safely and
easily.
When a heavily loaded carrier of the invention, with its tracks
fully on the floor FF, is to be moved into the tilted position
shown in FIG. 3, considerable force is required to cause the
lifting arm 18 to extend from the frame of the carrier. It will be
understood from FIGS. 7 and 8 that when the thrusters 20.1 are
extended (by operation of their individual electric motors), the
cam 26 is caused to pivot clockwise about its connection to the
lifting arm and the rounded cam edge 26.2 bears against the cam
follower rollers 26.4 to increase the distance between the pivotal
mounting of the cam and its contact with the rollers 26.4. When the
cam has reached the position shown in FIG. 7, further pivotal
movement of the cam may be restrained by means of stops or the
like, and the thrusters 20.1 form a sufficiently large angle with
the lifting arm 18 so that further extension of the thrusters
swings the lifting arm further from the frame and into the position
shown in FIG. 3. Similarly, when the carrier, loaded and in the
position shown in FIG. 3, is to be lowered into flush engagement of
its tracks with the floor, the thrusters are retracted and the cam
follower rollers 26.4 descend into contact with the cam edges 26.2,
as shown in FIG. 7. In this position, the cam aids in bearing the
weight of the carrier frame. As the thrusters 20.1 are further
retracted, the cam rotates counterclockwise into the position shown
in FIG. 8 in which the lifting arm is fully retracted within the
frame. In this manner, the cam and cam follower provide an
additional source of lifting power when the thrusters approach a
position parallel to the lifting arms.
Referring again to FIG. 7, it will be understood that the
rearwardly extending bogie wheels 36 (supported by tubing sections
34) may be attached to the carrier when the latter is in a
horizontal position as in FIG. 8. As the carrier is thereafter
lifted upwardly to e.g., the position of FIG. 7, the rear bogie
wheels encounter the ground and the rearward end of the track is
accordingly lifted from ground contact, rendering the carrier
free-wheeling. Similarly, the forward bogie wheels 36 (supported by
tubing sections 13.4a ) may be attached to the carrier only when
the carrier is tilted at a significant angle to the ground, as in
FIG. 3. Subsequent lowering of the carrier brings the forward bogie
wheels into contact with the ground, and the track is lifted from
ground contact as before to render the carrier free-wheeling. With
either location of the bogie wheels, the carrier may be so tilted
as to bring both the bogie wheels and the rearward end of the track
into engagement with the ground.
While we have described a preferred embodiment of the present
invention, it should be understood that various changes,
adaptations, and modifications may be made therein without
departing from the spirit of the invention and the scope of the
appended claims.
* * * * *